| 摘要 |
PROBLEM TO BE SOLVED: To provide an image reader which determines a shading abnormality due to dirt such as dust on an optical path of a fixed image reading means appropriately and improves image quality while enhancing versatility. SOLUTION: A copying device 1 reads a second reading roller 26 being a white reference member to a contact image sensor 27 at prescribed timing, and a shading data generation circuit 71 generates shading data from the obtained image data. An abnormality detection circuit 72 detects a minimum value of the shading data, compares the minimum value with a prescribed comparison reference value, determines that shading data are abnormal when the minimum value is smaller than the comparison reference value, and performs shading data abnormality determination processing for determining the abnormality on the basis of the shading data. When the abnormality detection circuit 72 determines that shading data are abnormal, the operation of reading an original is stopped. COPYRIGHT: (C)2005,JPO&NCIPI
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